How the phone alerts system that rattled Hawaii works
The false alert Saturday morning that a ballistic missile was heading towards Hawaii was sent to phones through a system that involves multiple government agencies and wireless carriers.
Why it matters
What happened in Hawaii is the highest-profile error in recent memory involving a national system that has drawn controversy in the past. The Federal Communications Commission said Saturday it would investigate the false alert, which Sen. Brian Schatz tweeted was "based on a human error."